Image data acquired with imaging devices, preferably two-dimensional imaging devices, are often used to match or register an object, such as a body of a patient or a body portion of a patient, for example, to pre-operatively acquired spatial presentations of the object. Registration calibration of an imaging device involves the determination of parameters representing a transformation or mapping of spatial positions in a three-dimensional coordinate system or operating space to imaging data projected on a (preferably) planar imaging surface of an imaging device. The transformation or mapping is also known as registration mapping. A registration mapping of an imaging device enables the combination of image data representing two-dimensional projections of a three-dimensional object with a three-dimensional coordinate system or operating space. In image guided surgery, a spatial representation of an object, a body of a patient or a body portion of a patient may be determined in relation to a predetermined three-dimensional coordinate system or operating space.
Combinations of two-dimensional image data of an object with three-dimensional representation of that object may comprise the calibration or registration of the three-dimensional object representation relative to a coordinate system or operating space common to the imaging device and the object. The combinations also may enable the combination of image data acquired of an object in proper spatial relation to the object on a computer display, for instance. Calibration or registration of an imaging device as well as the combination of image data with object representations in a three-dimensional coordinate system or operating space can use an acquired location and orientation of the imaging device relative to the spatial coordinate system or operating space at the time of imaging the object.
A locating or tracking device may be used to determine position and orientation of an object in a three-dimensional coordinate system or operating space by means of an array of activated markers attached to the object. By receiving signals transmitted from the markers with a sensor or sensors in different spatial positions and orientations, the position and orientation of the marker array and, thus, the position and orientation of the object to which the marker array is attached may be determined. An example of a system for tracking the spatial position and angular orientation of an object may be found in U.S. Pat. No. 5,828,770.
EP 1 629 789 A1 describes a method for verifying a registration of fluoroscopic images. The accuracy of the registration is verified using a phantom with a metallic plate carrying a predetermined pattern. The phantom is tracked by a navigation or tracking system and a three-dimensional model of the phantom pattern is overlaid to an acquired image using a registration mapping, thus allowing for the visual verification of the overall registration of the acquired image. However, this method basically comprises imaging an object with a known phantom structure in a known position and orientation and overlaying a three-dimensional model of the phantom structure to the image. In this method no change or modification to the pre-calculated registration mapping can be applied.